Tests were made of the locked-wheel stopping distances of four tire combinations on glare ice, on wet and dry asphaltic concrete, and on wet and dry portland cement concrete pavements. Identical cars with highway tread tires on four wheels, with plain snow tires on the rear wheels, with studded snow tires on the rear wheels, and with studded snow tires on four wheels were tested at speeds up to 50 mph and at temperatures from -5 to 33 f. On glare ice, snow tires gave no consistent improvement in stopping distance, compared with standard highway tires. Studded tires on the rear wheels resulted in a significant reduction in stopping distance, and studded tires on all four wheels resulted in a reduction in stopping distance that was more than twice the reduction with studs in the rear tires only. The improvements were greatest at ice temperatures near the freezing point. While the improvements decreased with decreasing ice temperatures, these improvements did not disappear at temperatures near -5f, as suggested by earlier research. On asphalt pavements, no significant differences in stopping distances were found on either wet or dry surfaces. On concrete pavements, studded tires were found to give small but significant increases in stopping distances on both wet and dry surfaces.
Samenvatting